[1][2] Del Rey wrote the song with Mike Hermosa and both produced it with Jack Antonoff, Drew Erickson, and Zach Dawes.

The song was written by Del Rey and Mike Hermosa, with whom she also co-produced it, alongside Jack Antonoff, Drew Erickson, and Zach Dawes.

She had read that "the [tunnel's] mosaic ceilings were still perfectly preserved, but no one could get in", and was compelled to write a song inspired by Nilsson's track using her own metaphors.

[5] There is no known connection to the tunnel under Ocean Boulevard at Sea Mist Resort in Myrtle Beach, South Carolina, built in the 1980s but no longer used as of 2022.

[8] Sam Sodomsky of Pitchfork described the song as a "slow, dreamy ballad filled" with "incidental moments" and found the tunnel in the title to be "less a geographic focal point than a window into the potential she sees in the most familiar scenes and well-traveled routes".